php mysql数据库操作类

<?php
class DB {
    private $host = 'localhost';
    private $user = 'username';
    private $pass = 'password';
    private $db = 'database_name';
    private $conn;

    public function __construct() {
        $this->conn = new mysqli($this->host, $this->user, $this->pass, $this->db);
        if ($this->conn->connect_error) {
            die("Connection failed: " . $this->conn->connect_error);
        }
    }

    public function query($sql) {
        return $this->conn->query($sql);
    }

    public function insert($table, $data) {
        $keys = implode(', ', array_keys($data));
        $values = implode(', ', array_map(function($value) { return "'$value'"; }, array_values($data)));
        $sql = "INSERT INTO $table ($keys) VALUES ($values)";
        return $this->query($sql);
    }

    public function update($table, $data, $where) {
        $set = implode(', ', array_map(function($key, $value) { return "$key = '$value'"; }, array_keys($data), array_values($data)));
        $sql = "UPDATE $table SET $set WHERE $where";
        return $this->query($sql);
    }

    public function delete($table, $where) {
        $sql = "DELETE FROM $table WHERE $where";
        return $this->query($sql);
    }

    public function close() {
        $this->conn->close();
    }
}
?>

public function query($sql, $params = []) {
    $stmt = $this->conn->prepare($sql);
    foreach ($params as $param) {
        $stmt->bind_param('s', $param); // 's'表示参数类型为字符串
    }
    $stmt->execute();
    return $stmt;
}

public function __destruct() {
    $this->close();
}